Airway infection with respiratory syncytial virus (RSV) is associated with worsening airway function in healthy infants and young children as well as patients with lung diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis. Efficient clearance of RSV from the lung requires airway epithelial cell participation in type I interferon-dependent immunity. The specific aims of this proposal are based on four observations regarding expression of antiviral genes in human airway epithelial cells after RSV infection: 1) airway epithelial cells response to both type I and II interferons by expression of antiviral proteins; 2) RSV infection selectively inhibits type I interferon signal transduction inside airway epithelial cells; 3) RSV inhibits type I interferon-induced Stat1 phosphorylation; and 4) RSV rapidly downregulates Stat2 expression. Based on these observations, we hypothesize that RSV may possess multiple mechanisms that modulate interferon-dependent immunity, but a critical mechanism for this effect is through decreased expression of Stat2 in human airway epithelial cells. It is likely that RSV evolution has generated these mechanisms in order to allow viral subversion of the airway defense response. The overall goal of this proposal is to generate a better understanding of the biochemical basis for RSV effects on antiviral gene expression in human airway epithelial cells and uncover strategies for selectively modifying damaging viral effects but not beneficial immunity in airway epithelium. Accordingly, our specific aims are to: I. Identify RSV effects on type I interferon signaling in airway epithelial cells. This aim will take advantage of human airway epithelial cell models and their sensitivity to RSV infection and interferon-dependent gene activation. Systematic evaluation of viral effects will be accomplished by assessment of the type I interferon JAK-STAT signaling pathway from receptor ligation to STAT phosphorylation. Because RSV may affect more than one-step in type I interferon signaling, viral effects on type I interferon-induced antiviral gene expression that are independent of STAT activation will also be identified. II. Develop strategies to overcome RSV effects on type I interferon signaling. This aim will take advantage of the same airway epithelial cell model systems for RSV infection and interferon-dependent gene activation. Modulation of proteasome function and viral protein expression will be used to bypass RSV effects and restore type I interferon-dependent signal transduction, gene expression, and antiviral effects in airway epithelial cells.